Swimming pools and spas are well known and provide recreational and health benefits to many people across the United States. Swimming pools and spas typically have water circulation systems that include electrical devices such as pumps and heaters. Further, many pools and spas have submersible lights located under the waterline to illuminate the water at night, thereby making the pool or spa safe and aesthetically appealing to swimmers.
Because of such electrical devices, swimming pools and spas are subject in most jurisdictions to restrictive codes intended to reduce the chance of accidental electric shock to swimmers. Typically, all conductive elements associated with a pool or spa, including submersible lights, are grounded in a conductive net. Additionally, a separately grounded electrical panel supplies power to electrical devices around the pool, such as transformers, pumps and lights.
A conventional submersible pool light typically is mounted within a conductive niche that is integrally associated with the side of the pool and is electrically grounded to the pool grounding net. This niche has a dome-shaped housing featuring an opening that is generally aligned with the pool wall and an interior cavity that is sized to accept a pool light. The interior cavity of the niche extends underground away from the pool wall so that the pool light can be mounted flush with the wall of the pool. The rear of the niche has a port that provides a sealed opening for a power cord to extend from the light to the pool's electrical panel. The front of the light does not seal the niche from the pool water: instead, pool water is admitted into the niche to cool the light.
The aforementioned conventional submersible pool light has a housing with an electric light bulb sealed therein, a lens located in front of the light bulb and a bezel around the lens to mount the light to the niche and cover the periphery of the niche for aesthetic purposes. This pool light typically has at least one electrically conductive element, such as a metal reflector mounted adjacent to the light bulb or a metal housing or other metal components. Accordingly, this pool light must be grounded to the pool's conductive net by a ground wire. The power cord of this light also contains a ground conductor leading to the pool's electrical panel.
While pool lights of the previously described type are generally acceptable, under certain circumstances such lights can have certain drawbacks. In particular, the electrically conductive reflector of the light can radiate electrical energy into a pool or spa if a fault occurs elsewhere in the pool's electrical service. Normally, if the electrical service of the pool has been properly installed and maintained the effect of such a fault will be minimal. However, sometimes the electrical service is not properly installed or maintained. In such cases, a fault on the electrical service ground can cause electricity to radiate from the conductive reflector, housing or other metal components, into the pool, resulting in harm to swimmers. Because of this possibility, submersible lights are required to be installed at least 18 inches below the waterline, where radiation of electricity would cause less harm to swimmer. In particular, because a shock from the light would be concentrated in a location away from the waterline, the heart and head of a typical swimmer would be less likely to bear the brunt of the electric shock.
There is another requirement that a pool light must satisfy for it to be mounted less than 18 inch below the waterline. This requirement mandates that the light withstand a predetermined impact so that accidental breakage of the light by a swimmer is less likely. Conventional pool lights have previously had glass lenses because of the high temperature of the light bulb, which must be sized to provide adequate light to the pool. Because glass lenses are relatively brittle, they have sometimes been unable to satisfy the aforementioned impact requirement.
The aforementioned requirement for mounting a pool light less than 18 inches below the waterline is of great concern because many pool and spa owners wish to install lights in the shallow end of the pool or in steps that are less than 18 inches below the waterline. Considering that pool walls often curve at depths of less than 18 inches to blend with the bottom surface and that light niches are intended for installation in flat wall surfaces, the typical pool therefore has limited locations for pool lights because they must be mounted in flat wall surfaces 18 inches below the waterline. Accordingly, the areas where conventional pool lights can be located are limited, thereby unduly restricting the illumination of the pool.
This 18 inch depth requirement also gives rise to another concern, namely, efficient and aesthetic lighting of the pool. Generally speaking, a specific amount of light must be reflected from the pool light onto the walls and bottom of a pool to provide the illumination necessary for a safe and inviting pool. However, when a pool light illuminates a pool, it does so with some inefficiency because some of its light escapes directly from the pool by crossing the flat water-to-air boundary. Accordingly, if some of the light escapes from the pool without illuminating the sides or bottom, a higher power light is required to provide such a safe and inviting appearance for swimmers. This inefficient illumination results in higher electricity bills for the operator of the pool and increases the cost of the light, which has a higher power light bulb than would otherwise be needed.
The light that escapes from a lit pool intersects the air-to-water boundary at an angle of incidence that is less than a reference angle known as the "critical angle." Both the angle of incidence and the critical angle are measured from the normal to the flat water-to-air boundary. For a water-to-air boundary, an angle of incidence of 48.5 degrees or more will cause total reflection of light back into the pool. Accordingly, pool lights mounted at the previously mentioned 18 inch depth tend to be inherently inefficient because some of their light will intersect the waterline at an angle of less than 48.5 degrees, thereby directly escaping without ever reflecting off of the pool's bottom or walls.
Another submersible light has been developed in an effort to address the foregoing problems. While this light is generally effective in lighting pools, under some circumstances it may be subject to the same drawbacks discussed above. In particular, this light utilizes an electrically conductive metal reflector and a glass lens. The metal reflector requires a ground wire connected to the pool's conductive net, which increases the manufacturing cost of the light. Furthermore, under certain circumstances, such as an incorrect or damaged installation, there is a risk that the metal reflector could radiate electrical energy into the pool and harm swimmers. The glass lens of this light also could have difficulty satisfying the impact test for the light to be mounted less than 18 inches below the waterline. The pool light shown in the Poppenheimer U.S. Pat. No. 5,349,505, may have some of the characteristics described above, although applicants are not aware of any specific information regarding this light beyond what is shown in the patent.
Another drawback of conventional submersible pool lights is the difficulty of servicing them. Periodically, a pool light must be removed from its niche to replace a burnt-out bulb or attend to other service or maintenance. Typically, conventional pool lights have a power cord long enough to extend from the niche to the sidewalk (commonly referred to in the pool industry as the "deck") next to the pool to allow the light to be brought above the waterline for servicing once it has been removed from the niche. Once brought out of the niche and onto the pool sidewalk, a conventional pool light is difficult to disassemble because it has many mechanical fasteners holding a bezel or face plate onto its housing. These fasteners must be removed with tools, which takes time and effort. These mechanical fasteners are required at least in part to provide a large force to hold a conventional axial seal between the faceplate and the housing.
Finally, when the light is reassembled, it must be re-inserted into the niche. Such re-insertion is difficult because the long power cord must be located in the niche, which must accommodate the light as well. Although the power cord can be wrapped around the housing of the light (which is usually tapered), the light typically has nothing to hold the coiled cord. Accordingly, the cord can slide off the housing of the light and create an obstruction that blocks the insertion of the light into the niche. Such interference only makes the servicing of the many-fastener light more awkward, difficult and frustrating.
It should, therefore, be appreciated that there is a need for a submersible light that has the following features: no conductive elements requiring grounding, a tough lens to withstand impacts from swimmers, and quick and easy serviceability. The present invention fulfills all of these needs.